Cyclic dependency errors - Rigging problems with stretching
So after inspecting the file the problem is driver on Y axis of mel1200_center_IK bone (the one in the middle of the mechanism).

The "cyclic dependency" is between this driver and both IK constraints (bone_brazo, bone_pivot) and the base (bone_control bone) of both IK bone chains.

I've put the "cyclic dependency" into quotation marks, because logically on bone level there is no cycle - the error is on Blender side and on how it evaluates dependencies and drivers. You hit a limitation that solves the new dependency graph.

Enable it and the rig will update correctly.



Your other option is to build the rig differently either with constaints or drivers, but not mixing them. You can substitute the driver with this to solve the issue:



I suggest to get rid of your other drivers as well (me1200_bone_pestillo) and solve them with constraints only.